Investing

Investing into a building immediately grants a one time Primary Boost, to only the investing player.
The investment also provides a Secondary Boost lasting 30 minutes to all players in The Town.
The duration of secondary boosts can be extended by investing again.
Secondary Boosts have a display icon on the right side of the screen while viewing The Town.
For example, if you invest once to the Sawmill, you will immediately receive wood as your primary boost, and all members of your town will produce more wood per hour.
If you were to use the slider to provide 3x a single investment, you would receive 3x that amount of wood, and increase the wood production for a duration 3x longer.
So it's more efficient to invest small amounts in succession instead of one bigger amount at once.

Member Contributions

The level of each Building in the Town is the sum of investments among all players in the Town. If 3 players each have 10,000 gold invested in the Town Hall, all players would then have a Town Hall with a total of 30k investment. If one of the 3 players leaves the city, the Town Hall would then be downgraded to 20k. The player that leaves get their 10k investment back, and carry it to any new city they join.

Worker Buildings

The level of Worker Buildings restrict the maximum level of Workers.
The Primary Boost provides an immediate flat amount of experience to each Worker corresponding to that Building.
This boost does not roll over experience into the next level of a Worker if that Worker has reached maximum level.
The Secondary Boost provides a Skill increase in addition to the amount provided by hired Workers.
The Skill amount from this Secondary Boost cannot provide Skill beyond the Discipline restriction set by a player's Workstations.
This amount provides no bonus if a player does not either the corresponding Workstation or at least 1 Worker with the appropriate Skill.

Hero Buildings

The level of Hero Buildings restrict the maximum level of Heroes.
The Primary Boost provides an immediate flat amount of experience to each Hero corresponding to that Building.
This boost does not roll over experience into the next level of an Hero if that Hero has reached maximum level.
The Secondary Boost provides a flat +25% to the Power of each Hero corresponding to that Building.
This is an additive increase of +25% to (Hero Base Power + Item Power).
Having the Set Bonus and the Hero Building's Secondary Boost provides a total of +50% to (Hero Base Power + Item Power).
For example, if Theor has 1,000 Power from his base stats and items, either the Set Bonus or the Training Hall Secondary Boost will bring his total Power to 1,250.
Having both active will bring his total Power to 1,500.